This patent application claims priority based on a Japanese patent application, 2000-145975 filed on May 18, 2000, the contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a probe card allowing signals to be transmitted between an integrated circuit and semiconductor testing equipment, especially to a probe card which can transmit high frequency signals to an integrated circuit having a plurality of pads on a narrow pitch area.
2. Description of the Related Art
When an integrated circuit is manufactured, testing the electric characteristic of the integrated circuit must be performed during manufacture. In order to perform this test, the installation of a transmission path for a test signal to be transmitted between a wafer where the integrated circuit is manufactured and semiconductor testing equipment is required. The transmission path may include a contactor on its front-end portion, and the test signal generated by the semiconductor testing equipment is provided to the integrated circuit by contacting the contactor to a contact terminal of the integrated circuit. Recently, as semiconductor devices operating at high frequency have been rapidly developed, the semiconductor testing equipment, the contactor and the transmission path between the semiconductor testing equipment and the contactor have been required to be ready for high frequency operation. Moreover, as density degree (or degree of integration) of recent semiconductor devices has increased remarkably, it has been required to develop a transmission path through which test signals can be provided to an integrated circuit having a plurality of pads on a narrow pitch area.
FIG. 1 shows a schematic diagram of a conventional contacting unit 10 through which a high frequency test signal can be transmitted between semiconductor testing equipment and a circuit under test, which is being tested. The contacting unit 10 includes a contactor 12, a coaxial cable 14 and a support-and-fixing unit 16. The contactor 12 clings to a front-end portion of the coaxial cable 14, and, during a test, is contacted to a contact terminal (for example, a pad, a soldering ball, a gold bump) of the circuit under test. The coaxial cable 14 is connected to the external semiconductor testing equipment (not shown). The support-and-fixing unit 16 supports the coaxial cable 14 and fixes the position of the contactor 12.
The transmission of signals between the external semiconductor testing equipment and the circuit under test is performed through the coaxial cable 14. Therefore, when a high frequency signal is transmitted by using the contacting unit 10, attenuation of the transmitted signal can be greatly reduced.
FIG. 2 shows a diagram of a portion of the contacting unit 10 near the contactor 12 in the direction of arrow A of FIG. 1. As shown in FIG. 2, the coaxial cable 14 has a signal line 18a for transmitting signals and a grounding line 18b for grounding. The contactor 12 includes a contactor 12a connected to a signal line of the circuit under test and contactors 12b and 12c connected to a grounding unit of the circuit under test. The contactors 12a, 12b and 12c are formed to be xe2x80x9cair-coplanarxe2x80x9d and maintain an impedance matching state almost until its front-end.
FIG. 3 shows the contactor 12 contacted to the circuit under test. The contactor 12a is contacted to the signal line 20a of the circuit under test, and contactors 12b and 12c are contacted to the grounding unit 20b and 20c of the circuit under test. The contacting unit 10 having the coaxial cable 14 can transmit high frequency signals of more than 100 GHz. Recent development of the integrated circuit is intended not only to increase speed operation but also to increase minuteness and increase integration of the circuit. According to the contacting unit 10 shown in FIG. 1, since the pitch of the contactor 12 is limited by the diameter of the coaxial cable 14, it is impossible to perform a test on a highly integrated circuit having pads of narrow pitches. Further, as the integration degree of the circuit is increased, since the number of pads formed on the circuit is more than several thousand, it is unreasonable in the cost aspect to form the contacting unit 10 shown in FIG. 1 as many as the number of the pads. Further, operating frequency of the next generation integrated circuit is in the range of 1 to several Giga-Hertz (GHz) and the contacting unit 10 is able to transmit high frequency signals of more than 100 GHz frequency band, but at present, it is not required to transmit such high frequency signals of more than 100 GHz frequency band.
Besides the contacting unit 10 shown in FIG. 1, a probe card having a plurality of contactors on a narrow pitch area is conventionally used for testing a circuit having a plurality of pads on a narrow pitch area. This probe card is required to be faster and have more pins on a narrower pitch. Further, the probe card is also required to have fine positioning ability and scrub function to perform sliding operation against pads of the circuit under test, to be light in weight for preventing deformation of the probe card and the wafer due to the weight, and to have area-array adaptability to a circuit of full-face terminal type. Further, in order to prevent waveform distortion during a test, a characteristic impedance from the input/output terminal of the semiconductor testing equipment and the contact terminal (pad) of the circuit under test must be maintained to be a predetermined value. Hereinafter, four (4) kinds of conventional probe pins used for the probe card are described in detail, and weak points of them are also described.
FIG. 4 shows conventional probe pins of a horizontal needle probe type. According to the horizontal needle probe type, a needle of diameter 200xcx9c300 um is used, wherein the needle is made of a metal like W, ReW, BeCu or Pd and has a tapered end. According to the conventional type, since the end of the needle is as long as 20 mm, the characteristic impedance is changed on the end area and reflection noise is generated. Therefore, measurable maximum frequency is as low as 0.2 GHz. Further, since this type of probe pin is made by hand, it is difficult to accomplish area-array adaptability, high density, low weight and fine positioning ability. Moreover, since the needle made of W, ReW, BeCu or Pd has crystalline grains, scrapes generated through scrubbing with the pad enter into the crystalline grains of the needle made of this kind of material after repeated contact with the pad of the circuit under test, and, as a result, contact resistance is increased.
FIG. 5 shows another conventional probe pin of a vertical needle probe type. The vertical needle probe type is developed to achieve the area-array adaptability and high density, which were problematic of the horizontal needle probe type, but the achievement level is still unsatisfactory. Further, compared with the horizontal type, the vertical needle probe type is at least 1.5 times heavier in weight, and it is impossible to achieve the goal of being light weight. According to the structure of the vertical type, since it is difficult to perform sliding operation, it is impossible to achieve satisfactory scrub function.
FIG. 6 shows conventional probe pins made by the membrane method. The membrane method is developed to accomplish goals of high speed, high density and area-array adaptability. According to the membrane method, metal bumps as probe pins are formed on the wiring substrate of polyimide film. The height of a metal bump is as low as dozens of micrometers (um), and it is possible to form a transmission path just in front of the metal bump, so that it is possible to achieve high speed operation. According to this method, however, since load is applied in the vertical direction, it is difficult to achieve a powerful scrub function. Further, since polyimide film is used as the substrate, the polyimide film is not uniformly expanded when a high temperature test is performed on the LSI, so that position alignment between the pads of the circuit under test and the metal bumps is not maintained.
FIG. 7 shows conventional probe pins made through photolithography plating. According to photolithography plating, it is possible to achieve the goals of high precision, high density and having many pins. Further, since it is possible to form a transmission line to the base of a probe pin, it is possible to achieve high speed operation. According to the structure, however, it is difficult to achieve area-array adaptability.
According to a U.S. Pat. No. 5,613,861, there is disclosed a method for manufacturing a probe by using an internal stress gradient of a thin film. MoCr is used as a material for this probe. However, this method has poor reproducibility because it uses internal stress, and it is difficult to form probes in the same shape.
According to Donald L. Smith, et. Al., in their xe2x80x9cFlip-Chip Bonding on 6-um Pitch using Thin-Film Microspring Technologyxe2x80x9d ((Proceedings of 48th Electronic Components and Technology Conf.; Seattle, Wash. (May, 1998):c1998 IEEE), there is disclosed a method for forming a MoCr thin film having an internal stress gradient in the direction of thickness using a step-by-step increase of pressure while depositing the thin film. According to this method, since the reproducibility of controlling the stress is poor, it is difficult to form probes in the same shape.
According to Soonil Hong, et. Al., in their xe2x80x9cDESIGN AND FABRICATION OF A MONOLITHIC HIGH-DENSITY PROBE CARD FOR HIGH-FREQUENCY ON-WATER TESTINGxe2x80x9d (IEDM 89, pp. 289-292), there is disclosed a method for manufacturing a probe by accumulating thin films of which stress are different. According to this method, since a plurality of thin films are formed, it is difficult to achieve uniform characteristics between probes and to manufacture probes of the same characteristic.
According to Yanwei Zhang, et. Al., in their xe2x80x9cA NEW MEMS WAFER PROBE CARDxe2x80x9d (0-7803-3744-1/97 IEEE, pp. 395-399), there is disclosed a method for manufacturing a probe using bimorphs. Since this method uses a heater, the structure is complex due to the wirings for the heater.
According to Shinichiro Asai, et. Al., in their xe2x80x9cProbe Card with Probe Pins Grown by the Vapor-Liquid-Solid (VLS) Methodxe2x80x9d (IEEE TRANSACTIONS ON COMPONENTS, PACKAGING AND MANUFACTURING TECHNOLOGY-PART A, VOL. 19, NO. 2, JUNE 1996), there is disclosed a xe2x80x9cwhisker-probexe2x80x9d which is grown vertically from the substrate. Since this probe is as long as 1xcx9c3 mm, it is difficult to achieve high speed operation and light weight.
As described before with reference to FIGS. 4 to 7 and other references, the conventional probe pins are not able to achieve the above characteristics which are the described goals. Therefore, it is required to develop a probe card which can achieve the goals of high speed operation, high density, many pins, area-array adaptability, scrub function, light weight and fine positioning.
Therefore, the present invention has a goal of providing a probe card which can transmit a high-frequency signal of more than 1 GHz frequency.
It is an object of the present invention to provide a probe card which can achieve the above described goal and a method for manufacturing thereof. The above-described object can be accomplished by combinations of features of the independent claims. Dependent claims prescribe further useful concrete examples of the present invention.
In order to achieve the above described goals, the first aspect of the present invention provides a probe card electrically coupled to a plurality of contact terminals provided on a circuit under test for performing signal transmission between the circuit under test and an external semiconductor testing equipment, including: a substrate; a plurality of signal transmission paths formed on the substrate; and a plurality of contactors formed on ends of the plurality of signal transmission paths on one side of the substrate, wherein the plurality of contactors are made of an amorphous material (or, metallic glass material) including a supercooled liquid phase region and contacted to the contact terminals provided on the circuit under test.
According to the first aspect of the present invention, by forming a metallic glass contactor (minute probe pin) by micromachining technology, it is possible to provide a probe card which can transmit a high-frequency signal of more than 1 GHz frequency to an integrated circuit having a plurality of pads on a narrow area. Further, since micromachining is used, it is possible to manufacture a plurality of probe pins for high speed simultaneously.
According to a feature of the first aspect, the contactor is formed to be separated from the substrate.
According to another feature of the first aspect, the contactor is extended to a predetermined direction from a surface of the substrate. The predetermined direction is a direction away from the surface of said substrate.
According to another feature of the first aspect, the contactor is bent in a predetermined direction from said surface of said substrate.
According to another feature of the first aspect, the contactor has a vertical elasticity against a surface of the substrate.
According to another feature of the first aspect, the contactor has vertical elasticity against the surface of said substrate in order to slide on the contact terminal of the circuit under test when they are contacted.
According to another feature of the first aspect, each of the plurality of the contactors has elasticity against the surface of said substrate. Each of the plurality of the contactors has different elasticity against the surface of said substrate.
According to another feature of the first aspect, at least a portion of the signal transmission path near the end of it is made of the same amorphous material used for the contactor. In this case, a portion of the signal transmission path near the end of it forms a single body together with the contactor.
According to another feature of the first aspect, the probe card further includes a grounding line, which is grounded, formed to be apart from and in parallel to the signal transmission path.
According to another feature of the first aspect, the probe card further includes a low-resistance unit having lower resistance than that of the signal transmission path, the low-resistance unit being formed near the signal transmission path.
According to another feature of the first aspect, the low-resistance unit is made of gold, copper, nickel, aluminum, platinum or rhodium.
According to another feature of the first aspect, the contactor includes a contacting point made of a contact-point material on an end of it.
According to another feature of the first aspect, the contactor is coated with a metal material.
According to another feature of the first aspect, the probe card further includes a voltage providing unit for providing a predetermined voltage, the voltage providing unit being provided on a backside of the one side of the substrate.
According to another feature of the first aspect, the voltage providing unit is a grounding conductor which is grounded.
According to another feature of the first aspect, the voltage providing unit is formed on an area other than areas of the backside of the substrate corresponding to areas of the one side of the substrate where the contactors are formed.
According to another feature of the first aspect, the substrate is made of a dielectric material or a semiconductor material, and the signal transmission path, the substrate and the grounding conductor form a microstrip line having predetermined characteristic impedance.
According to another feature of the first aspect, the probe card is formed on one side of the substrate and further includes a ground conductor layer, which is grounded, and a dielectric layer made of a dielectric material near the grounding conductor, and the signal transmission path is formed near the dielectric layer, and the signal transmission path and the dielectric layer form a microstrip line having a predetermined characteristic impedance.
According to another feature of the first aspect, the signal transmission path has a parallel transmitting unit formed to be in parallel with the surface of the substrate.
According to another feature of the first aspect, the signal transmission path has a penetrating-transmitting unit which is formed to penetrate the substrate in a direction of its thickness.
According to another feature of the first aspect, the signal transmission path has an internal transmitting unit extended in parallel with the surface of the substrate inside the substrate.
According to another feature of the first aspect, the signal transmission path has internal transmitting units disposed at different distances from the surface of the substrate.
According to another feature of the first aspect, a probe card further includes a plurality of contactors made of an amorphous material having a supercooled liquid phase region, wherein the plurality of contactors are electrically coupled to the contactors formed on one side of the substrate through the signal transmission paths and formed on the backside of the substrate.
According to another feature of the first aspect, the contactor has a sharp end which narrows towards the end.
According to another feature of the first aspect, the contactor has a two-fingered fork shape end, where each of the fingers has a sharp end.
In order to achieve the above described goals, the second aspect of the present invention provides a method for forming a contactor on a substrate of a probe card electrically coupled to a plurality of contact terminals provided on a circuit under test for performing signal transmission between the circuit under test and external semiconductor testing equipment, the contactor contacting to the contact terminal, including steps of: forming a sacrificial layer on a predetermined area of the substrate; forming an amorphous material layer including an amorphous material having a supercooled liquid phase region on the sacrificial layer and the substrate; forming a cantilever of an amorphous material including a free unit as a portion of it by removing the sacrificial layer between a portion of the amorphous material layer and the substrate, the free unit being separated from the substrate; and forming the contactor by bending the free unit toward a predetermined direction from the substrate.
According to another feature of the second aspect, there is provided a method for forming a contactor on a substrate of a probe card electrically coupled to a plurality of contact terminals provided on a circuit under test for performing signal transmission between the circuit under test and an external semiconductor testing equipment, the contactor contacting to the contact terminal, including steps of: forming an amorphous material layer including an amorphous material having a supercooled liquid phase region on the substrate; forming a free unit on a portion of the amorphous material layer by removing a portion of the substrate under the portion of the amorphous material layer, the free unit being separated from the substrate; and forming the contactor by bending the free unit toward a predetermined direction from the substrate.
According to another feature of the second aspect, the step for forming a contactor includes a step for bending the free unit away from the substrate.
According to another feature of the second aspect, the amorphous material layer is formed by sputtering the amorphous material.
According to another feature of the second aspect, the step for forming the contactor includes a step for causing a plastic deformation of the free unit toward a predetermined direction from the substrate.
According to another feature of the second aspect, the step for forming the contactor includes a step for heating the free unit.
According to another feature of the second aspect, the step for forming the contactor includes a step for heating the free unit when the free unit is disposed under the substrate.
According to another feature of the second aspect, the step for forming the contactor includes a step for irradiating infrared light on the free unit.
According to another feature of the second aspect, the step for forming the contactor includes a step for irradiating infrared light on the free unit from both sides of the substrate.
According to another feature of the second aspect, the step for forming the contactor includes a step for providing a bending adjustor at a predetermined position toward a direction of gravity from the surface of the substrate.
According to another feature of the second aspect, the step for forming the contactor includes a step for providing a bending adjustor of higher transmittance for infrared light than the substrate.
According to another feature of the second aspect, the step for forming the contactor includes a step for providing a bending adjustor having flatness less than +/xe2x88x9210 um.
According to another feature of the second aspect, the step for forming the contactor includes a step for providing a bending adjustor having flatness less than +/xe2x88x922 um.
According to another feature of the second aspect, the step for forming the contactor includes a step for providing a quartz glass substrate as a bending adjustor.
According to another feature of the second aspect, the step for forming the contactor includes a step for providing a quartz glass substrate including a position determining unit for determining the predetermined position toward a direction of gravity from the surface of the substrate.
According to another feature of the second aspect, the step for forming the contactor includes a step for providing a bending adjusting member including an engaging unit for suppressing movement of the substrate in a direction of gravity and a bending adjustor for determining the predetermined position toward a direction of gravity from the surface of the substrate.
According to another feature of the second aspect, the step for forming the contactor includes a step for controlling the amount of bending of the free unit by changing thickness of the bending adjustor.
According to another feature of the second aspect, the step for forming the contactor includes a step for providing a bending adjusting member having the bending adjustor made of a quartz glass substrate.
According to the third aspect of the present invention, there is provided a semiconductor chip including: a plurality of pads; and a plurality of contactors made of an amorphous material having a supercooled liquid phase region on the plurality of pads, wherein the contactor is extended to a predetermined direction from a surface of the pads.
According to another feature of the third aspect, the contactor is extended to a direction away from the substrate.
According to the third aspect of the present invention, there is provided a semiconductor device including a semiconductor chip having a plurality of pads, including: a plurality of electrode leads; and a package which packs the semiconductor chip, wherein the pads of the semiconductor chip and the electrode leads are electrically coupled to each other through contactors made of an amorphous material having a supercooled liquid phase region.
According to the third aspect of the present invention, there is provided a semiconductor device including a semiconductor chip having a plurality of pads, including: a plurality of external terminal balls; and a package which packs the semiconductor chip, wherein the pads of the semiconductor chip and the external terminal balls are electrically coupled to each other through contactors made of an amorphous material having a supercooled liquid phase region.
The above description does not necessarily list all features of the present invention, and combinations of the above features also can be construed as aspects of the present invention.